1. Field of the Invention
The present invention relates to an image pickup apparatus such as a camera. More particularly, the present invention relates to an apparatus configured to record data on a replaceable recording medium.
2. Description of the Related Art
As a recording medium for recording image data captured by shooting, a conventional digital camera uses a small-sized memory card including a semiconductor memory having a capacity of several hundreds of megabytes or several gigabytes. Such a conventional digital camera records the captured image data on a memory card inserted in a memory card slot provided at the camera body.
However, in the case of using a single memory card, only a limited number of images can be recorded on the memory card. That is, it is necessary for a user to use a plurality of memory cards to record a large number of images. Accordingly, the market has desired a recording medium of a larger capacity.
Under such an environment surrounding a semiconductor memory, a hard disk drive (HDD), which uses a magnetic disk as a recording medium, has recently been widely used as a recording medium having a larger capacity and is more inexpensive in terms of running costs. An HDD has been generally used as a peripheral device for a personal computer (PC). A universal serial bus (USB) connection method has been widely used to connect an HDD to a PC. In this regard, Japanese Patent Application Laid-Open No. 2001-238112 discusses a method for using an HDD externally connected to a digital camera as a recording medium.
In the case of using a USB-connected peripheral device, a PC, which generally serves as a host device, has a sufficient power supply source. Accordingly, it is not necessary for a user to be so much careful about managing a power supply to a peripheral device.
On the other hand, in the case where a USB-connected peripheral device, such as an HDD, is connected to a battery-driven mobile apparatus, such as a digital camera, which serves as a host device for the USB-connected peripheral device, it is necessary for a user to be careful about a power supply management for a system including the mobile apparatus and the peripheral device. That is, in this case, it is useful to provide and shift to a power saving mode, which enables low power consumption by positively stopping a power supply to a peripheral device.
With respect to a certain USB-connected peripheral device, more than a few seconds may be required from the time the peripheral device is powered on to the time the USB-connected device becomes finally active. In addition, with respect to a peripheral device, such as an HDD, more than a few seconds may be required from the time the built-in magnetic disk starts to rotate to the time data can be written on and read from the HDD.
When a shooting operation is performed with such an HDD connected to a digital camera (host device) as a recording medium, a user may lose an appropriate shooting opportunity. That is, the time required to shift from the power saving mode to the operable state (normal power consumption mode) is significant with respect to a performance of an electronic apparatus, such as a digital camera, which is required to respond quickly to a user instruction.
In this regard, when a recording medium, such as a memory card, is inserted into a memory card slot of a digital camera, the digital camera stores free space information, folder information, and file information about the inserted recording medium in a non-volatile memory in the digital camera. Such a digital camera can continue shooting operations based on the information about the recording medium stored in the digital camera until the recording medium is replaced with another recording medium.
Meanwhile, an HDD cannot be easily incorporated into a digital camera body. Accordingly, in the case of using an HDD as a recording medium for a digital camera, the HDD is externally connected to the digital camera via a cable, as an external recording medium.
When such an external recording medium is used, it is not easy to detect a connection or disconnection of the recording medium, contrary to a case of using a small-sized memory card that can be easily inserted into or dismounted from the camera body, in which case it is easy to detect a connection state by using a switch. Accordingly, in the case of using such an external recording medium, whether an external recording medium is connected (connection status) is detected by an electrical communication. However, when the power supply to the external recording medium is stopped in the power saving mode, the connection state cannot be detected.
Accordingly, when an external recording medium is replaced during a power saving mode, it cannot be detected that the external recording medium has been replaced. Thus, information about a recording medium stored in an image pickup apparatus may be different from information about a currently connected external recording medium.